1. Field of the Invention
The present invention relates to a conveyor chain in which lubricant oil is sealed in a raceway for a large number of bearing elements which are loosely inserted between a bush and a roller, serving as an inner and an outer race of the bearing in the link. More specifically, the invention relates to a conveyor chain for carrying and conveying heavy loads such as coils and slabs in the iron manufacturing field.
2. Related Art
A conveyor chain in which lubricant oil is sealed within a raceway in which a large number of bearing elements is loosely inserted between a bush and a roller of each link thereof is widely used as a conveyor chain for carrying and conveying heavy loads such as coils and slabs in the iron manufacturing field.
As shown in FIG. 11, such prior art conveyor chain 500 comprises, in each link thereof, a pair of inner link plates 510 separately disposed on right and left sides, a bush 520 press-fitted into bush holes 512 of these inner link plates 510, a roller 530 rotatably fitted around the bush 520, a link pin 540 inserted through the bush 520, a pair of right and left outer link plates 550 press-fitted to both ends of the link pin 540 and linking the adjoining inner link plates 510 mutually in a chain longitudinal direction, a plurality of bearing elements 560 loosely inserted between an outer circumferential surface 520a of the bush 520 and an inner circumferential surface 530a of the roller 530 and a pair of right and left thrust bearing annular members 570 press-fitted to the outer circumferential surface 520a of the bush 520 and disposed between an inner side surface 510a of the inner link plate 510 and end surfaces 560a of the bearing elements 560, and lubricant oil is sealed within the raceway for the bearing elements 560 as disclosed in U.S. Patent Publication No. 2003/0032511 [Japanese Patent No. 3719963].
In another example of a prior art conveyor chain shown in U.S. Pat. No. 6,742,935 [Japanese Patent No. 3563354], a thrust bearing annular member or retainer is disposed at both ends of a roller, grooves each having a semicircular shape in section, are formed respectively on an inner circumferential surface of the roller and an outer circumferential surface of the thrust bearing annular member between the roller and the thrust bearing annular member, the groove of the roller is vertically aligned with the groove of the thrust bearing annular member to form a void having a circular shape in section and an annular sealing member having a circular shape in section is disposed in this void substantially without gap (see FIG. 8c).